.header{
    margin:0 auto;
    width:100%;
    height:500px;
    background-color:#000;
    position:relative;
    z-index:0;
}
.header canvas {
    width:100%;
    height:500px;/*默认全屏显示 可自己设置高度640px*/
    display:inline-block;vertical-align:baseline;
    position:absolute;
    z-index:1;
}
.header .canvaszz{  /*用来解决视频右键菜单，用于视频上面的遮罩层*/
    width:100%;
    background-image: url(../../img/in_top_bj.jpg);
    height:500px;
    position:absolute;
    z-index:2;
    filter:alpha(opacity=40);
    -moz-opacity:0.4;
    opacity: 0.4;

}